Sex down under: the differentiation of sexual dimorphisms during marsupial development

2001 ◽  
Vol 13 (8) ◽  
pp. 679 ◽  
Author(s):  
Marilyn B. Renfree ◽  
Andrew J. Pask ◽  
Geoffrey Shaw
Keyword(s):  
Mammary Gland ◽  
Sexual Differentiation ◽  
Circulatory System ◽  
Excretory System ◽  
Mode Of Reproduction ◽  
Sexual Dimorphisms ◽  
Characteristic Features

Marsupials have many characteristic features that make them ideal models to study the control of sexual differentiation and development. They are distinguished from eutherian mammals in their mode of reproduction and their greater dependence on the teat and mammary gland than on the placenta for development. They give birth to a highly altricial young which completes its development while firmly attached to a teat, usually within the confines of a pouch. At birth, the marsupial neonate has a well-developed digestive, respiratory and circulatory system, but retains its fetal excretory system with a fully functional mesonephric kidney and undifferentiated gonads and genitalia.

scholarly journals Algorithm for detecting spherulite marker in human blood serum facies

2019 ◽  
pp. 109-113
Author(s):  
O E Malenova ◽  
L I Trubnikova ◽  
A S Yashina ◽  
M L Albutova
Keyword(s):  
Thin Film ◽  
Mammary Gland ◽  
Medical Diagnosis ◽  
Visual Analysis ◽  
Biological Fluids ◽  
Uterine Fibroids ◽  
Detection Methods ◽  
Atypical Form ◽  
Probable Presence ◽  
Characteristic Features

One of the effective methods of early medical diagnosis is the method of wedge dehydration. It is based on the analysis of facies images. Facia is a thin film of dried human biological fluids. The presence of special structures (markers) indicates various pathologies of the organism at their earliest stages. In this article, the algorithm for detecting spherulite marker on microscopic images of human serum facies is presented. The presence of spherulites on facies is the norm. However, the atypical form of spherulite is a marker of precancerous diseases: uterine fibroids, endometrial hyperplastic processes and the mammary gland. Due to the visual analysis of the marker, its characteristic features were identified. Then algorithmic detection methods for these features were developed. The decision on the probable presence of a marker was made if there was a combination of features of this marker. As a result of the application of the developed algorithm, most images of atypical spherulites were identified.

No direct contact between the excretory system and the circulatory system in Prostomatella arenicola Friedrich (Hoplonemertini)

Hydrobiologia ◽  
1988 ◽  
Vol 156 (1) ◽  
pp. 175-181 ◽  
Author(s):  
Thomas Bartolomaeus
Keyword(s):  
Direct Contact ◽  
Circulatory System ◽  
Excretory System

Sex determination in marsupials: evidence for a marsupial—eutherian dichotomy

1988 ◽  
Vol 322 (1208) ◽  
pp. 41-53 ◽  
Keyword(s):  
Sexual Differentiation ◽  
Reproductive Tract ◽  
Tammar Wallaby ◽  
Mammary Glands ◽  
Mammary Development ◽  
Female Reproductive Tract ◽  
The Other ◽  
Processus Vaginalis ◽  
Sexual Dimorphisms ◽  
Other Hand

In this paper, we review briefly the current state of knowledge about sexual differentiation in eutherian mammals, and then describe the situation in detail in two marsupial species: the North American opossum and the tammar wallaby. The conventional explanation for the genesis of all male somatic sexual dimorphisms in mammals is that they are a consequence of the systemic action of testicular hormones. In the absence of testes, the embryo will develop a female phenotype. We present evidence for the tammar wallaby that calls into question the universal applicability of this hormonal theory of mammalian sexual differentiation. We have shown that extensive somatic sexual dimorphisms precede by many days the first morphological evidence of testicular formation, which does not occur until around the third day of pouch life. Male foetuses, and pouch young on the day of birth, already have a well-developed gubernaculum and processus vaginalis, paired scrotal anlagen, and a complete absence of mammary anlagen, whereas female foetuses and newborn pouch young have a poorly developed gubernaculum and processus vaginalis, no scrotal anlagen, and well-developed mammary anlagen. Because it seems unlikely that the male gonad could begin hormone secretion until after the Sertoli and Leydig cells are developed, our results strongly suggest that some sexually dimorphic somatic characteristics develop autonomously, depending on their genotype rather than the hormonal environment to which they are exposed. We have been able to confirm the hormonal independence of the scrotum, pouch and mammary gland by administering testosterone propionate daily by mouth to female pouch young from the day of birth; although the Wolffian duct was hyperstimulated, there was no sign of scrotal development, or pouch or mammary inhibition. When male pouch young were treated with oestradiol benzoate in a similar fashion, there was hyperstimulation of the Müllerian duct and inhibition or pouch or testicular migration and development, but no sign of scrotal inhibition or pouch or mammary development. Our results in the tammar wallaby are consistent with the earlier studies on the opossum, whose significance was not appreciated at the time. Further evidence in support of this hormonal independence comes from earlier studies of spontaneously occurring intersexes in several species of marsupial, including the opossum and the tammar wallaby. An XXY individual had intra-abdominal testes and complete masculinization of the male reproductive tract internally, but externally there was a pouch and mammary glands and no scrotum. A similar picture was found in two XY individuals. On the other hand, an XO individual had hypoplastic ovaries, normal development of the female reproductive tract internally, and an empty scrotum. Thus the scrotum can develop in the absence of a testis, whereas the pouch and mammary glands can develop in the presence of one. These results suggest a fundamental dichotomy between marsupials and eutherians in their sex-determining mechanisms. Although both subclasses probably require a Y-linked gene or genes for testis determination, marsupials appear to use other X-linked genes to control the development of structures such as the scrotum, pouch and mammary glands. In eutherians, on the other hand, scrotal and mammary development appears to be entirely under hormonal control. The lack of any genetic interchange between the X and the Y during meiosis in marsupials has presumably resulted in a much greater degree of genetic isolation of one sex chromosome from the other than is the case in eutherians, and the small size of the marsupial Y suggests that marsupials may have progressed further than eutherians in capture of genetic material by the X from the ancestral Y. Marsupials seem destined to play a vital role in the years to come in the mapping of sex-linked genes and determining their modes of action. Clearly they have much to tell us about the evolution of sex-determining mechanisms in all mammals.

scholarly journals REPRODUÇÃO DE PEIXES DE RIACHO: ESTADO DA ARTE, MÉTODOS E PERSPECTIVAS

2021 ◽  
Vol 25 (02) ◽  
pp. 323-343
Author(s):  
Érica Pellegrini Caramaschi ◽  
◽  
Marcelo Fulgêncio Guedes Brito ◽  
Keyword(s):  
Life History Traits ◽  
Neotropical Region ◽  
Stream Fish ◽  
Natural Environments ◽  
Fish Reproduction ◽  
Mode Of Reproduction ◽  
Sexual Dimorphisms ◽  
Reproductive Life ◽  
Basic Studies ◽  
Reproductive Events

Stream fish reproduction is still poorly studied in natural environments, especially in the Neotropical region. In this chapter, we recollect some characteristics of fish reproduction and some questions to guide current research, as: Does sexual dimorphism occur in the species? Which is the mode of reproduction? When and where does the species reproduce? Which environmental factors trigger reproductive events? When does the reproductive life begin? Which is the fecundity? Most of these questions can be answered when we have many specimens available, captured at different periods of the year, measured, weighed and dissected following appropriate protocols. Obtained data represent life history traits that allow to categorize the species in reproductive styles related to parental care and to determine their accordance to models of reproductive strategy associated with the predictability of environmental conditions. We highlight some aspects to be considered in current and future field and lab procedures, such as the recognition of sexual dimorphisms, the importance of naturalistic observation and lab procedures. We draw attention to the advances in studies on reproductive modalities in fish groups well represented in streams, such as inseminating characiforms and viviparous cyprinodontiforms. Finally, we highlight gaps, urgencies, and current perspectives for studies on the reproduction of stream fish, with emphasis on the need for basic studies of species biology, on the importance for building theoretical references and for the conservation of stream habitats in all Brazilian biomes.

Society for Reproductive Biology Founders' Lecture 2006 Life in the pouch: womb with a view

2006 ◽  
Vol 18 (7) ◽  
pp. 721 ◽  
Author(s):  
Marilyn B. Renfree
Keyword(s):  
Sex Determination ◽  
Umbilical Cord ◽  
Sexual Differentiation ◽  
Comparative Genomic ◽  
Embryonic Diapause ◽  
Seasonal Breeding ◽  
Mode Of Reproduction ◽  
Genomic Biology ◽  
Marsupial Species ◽  
Reproductive Events

Marsupials give birth to an undeveloped altricial young after a relatively short gestation period, but have a long and sophisticated lactation with the young usually developing in a pouch. Their viviparous mode of reproduction trades placentation for lactation, exchanging the umbilical cord for the teat. The special adaptations that marsupials have developed provide us with unique insights into the evolution of all mammalian reproduction. Marsupials hold many mammalian reproductive ‘records’, for example they have the shortest known gestation but the longest embryonic diapause, the smallest neonate but the longest sperm. They have contributed to our knowledge of many mammalian reproductive events including embryonic diapause and development, birth behaviour, sex determination, sexual differentiation, lactation and seasonal breeding. Because marsupials have been genetically isolated from eutherian mammals for over 125 million years, sequencing of the genome of two marsupial species has made comparative genomic biology an exciting and important new area of investigation. This review will show how the study of marsupials has widened our understanding of mammalian reproduction and development, highlighting some mechanisms that are so fundamental that they are shared by all today’s marsupial and eutherian mammals.

533. Intramammary pressure changes in the lactating sow: I. The effect of oxytocin

1954 ◽  
Vol 21 (1) ◽  
pp. 19-30 ◽  
Author(s):  
W. G. Whittlestone
Keyword(s):  
Mammary Gland ◽  
Circulatory System ◽  
Recording System ◽  
Pressure Recording ◽  
Electronic Pressure ◽  
System Pressure ◽  
Order Of Magnitude ◽  
Two Phases ◽  
Pressure Changes ◽  
Lactating Sow

Using an electronic pressure recording system, pressure changes in the sow's mammary gland in response to injections of oxytocin and whole pituitrin have been recorded. The results suggest that an injection of oxytocin within physiological range may pass round the circulatory system twice, resulting in a small secondary pulse of pressure. Slow injections over periods of the order of 8–16 sec. are shown to produce a double rise in pressure, the two phases of which are of the same order of magnitude, suggesting a contraction followed by a period of relaxation and a further contraction.

scholarly journals On the generation of the marsupial animals; with a description of the impregnated uterus of the kangaroo

1837 ◽  
Vol 3 ◽  
pp. 278-280
Keyword(s):  
Mammary Gland ◽  
Mode Of Reproduction ◽  
History Of ◽  
Generative Organs

The author gives a history of the opinions which have been advanced relative to the generative organs and functions of the Marsupiata , an extensive order of quadrupeds, including animals nourished by every variety of food, and exercising very different powers of progression, yet exhibiting a remarkable uniformity in their mode of reproduction. In all the genera included in this family, the uterus is double; in most of them the vagina is also double; and there is always a single cloacal outlet for the excrementitious substances, and the products of generation. There is a corresponding uniformity in the male organs, which are bifurcated at the extremity, and have a double groove for the transmission of the semen; and the male has not only marsupial bones, similar to those of the female, but also a muscle, similar to that which surrounds and compresses the mammary gland in the female, winding round these bones like pulleys, and acting as cremasters for the retraction and compression of the testes.

scholarly journals Both Estrogen Receptor-α and -β Are Required for Sexual Differentiation of the Anteroventral Periventricular Area in Mice

Endocrinology ◽  
2006 ◽  
Vol 147 (1) ◽  
pp. 415-420 ◽  
Author(s):  
Cristian Bodo ◽  
Andrea E. Kudwa ◽  
Emilie F. Rissman
Keyword(s):  
Sexual Differentiation ◽  
Dopaminergic Neurons ◽  
Perinatal Period ◽  
Estrogen Receptor Α ◽  
Sexually Dimorphic ◽  
Wild Type ◽  
Cell Numbers ◽  
Sexual Dimorphisms ◽  
Series Of Experiments ◽  
Periventricular Area

Sexual dimorphisms in the hypothalamus are mediated in several cases by local aromatization of androgens to estrogens during the perinatal period. In this series of experiments, the contributions of the two estrogen receptors (ERs), ERα and ERβ, to the differentiation of the sexually dimorphic subpopulation of dopaminergic neurons in the anteroventral periventricular area (AVPV) was examined. In the first experiment, numbers of tyrosine hydroxylase (TH) immunoreactive (-ir) AVPV neurons in ERβ knockout and wild-type (WT) mice of both sexes were measured. In the second experiment, the average number of TH-ir neurons in the medial portion of the AVPV in ERα knockout, ERβ knockout, double-ER knockout, and WT mice of both sexes was calculated. In both experiments TH-ir cell numbers were sexually dimorphic as expected, with female individuals of all genotypes exhibiting more TH-ir neurons than WT males. Interestingly the average number of TH-ir neurons in all knockout males was significantly higher than in WT male littermates. In fact, TH-ir cell numbers in all knockout males were equivalent to females. In a final experiment, C57BL/6J female mice were treated during the first 3 postnatal days with either estradiol, or a specific agonist for one of the two ERs. Additional male and female pups received vehicle injections. Treatments with estradiol or either ER-specific agonist significantly reduced the number of TH-ir AVPV neurons in female brains. Our data demonstrate that both ERα and ERβ are involved in the sexual differentiation of the AVPV in mice.

scholarly journals Evolutionary history of sexual differentiation mechanism in insects

2021 ◽  
Author(s):  
Yasuhiko Chikami ◽  
Miki Okuno ◽  
Atsushi Toyoda ◽  
Takehiko Itoh ◽  
Teruyuki Niimi
Keyword(s):  
Sexual Differentiation ◽  
Evolutionary History ◽  
Sister Group ◽  
Protein Motif ◽  
Sexual Dimorphisms ◽  
History Of ◽  
Alternatively Spliced ◽  
The Common ◽  
Ancestral States ◽  
Female Specific

AbstractGain of alternative splicing gives rise to functional diversity in proteins and underlies the complexity and diversity of biological aspects. However, it is still not fully understood how alternatively spliced genes develop the functional novelty. To this end, we infer the evolutionary history of the doublesex gene, the key transcriptional factor in the sexual differentiation of arthropods. doublesex is controlled by sex-specific splicing and promotes both male and female differentiation in some holometabolan insects. In contrast, doublesex promotes only male differentiation in some hemimetabolan insects. Here, we investigate ancestral states of doublesex using Thermobia domestica belonging to Zygentoma, the sister group of winged insects. We find that doublesex of T. domestica expresses sex-specific isoforms but is only necessary for male differentiation of sexual morphology. This result ensures the hypothesis that doublesex was initially only used to promote male differentiation during insect evolution. However, T. domestica doublesex has a short female-specific region and upregulates the expression of vitellogenin homologs in females, suggesting that doublesex may have already controlled some aspects of feminization in the common ancestor of winged insects. Reconstruction of the ancestral sequence and prediction of the protein structure show that the female-specific isoform of doublesex has a long C-terminal disordered region in holometabolan insects, but not in non-holometabolan species. We propose that doublesex acquired a female-specific isoform and then underwent a change in the protein motif structure, which became essential for female differentiation in sexual dimorphisms.

Sign in / Sign up

Export Citation Format

Share Document