Avian Reproduction

There are about 10,400 living avian species belonging to the class Aves, characterized by feathers which no other animal classes possess and are warm-blooded vertebrates with four-chamber heart. They have excellent vision, and their forelimbs are modified into wings for flight or swimming, though not all can fly or swim. They lay hard-shelled eggs which are a secretory product of the reproductive system that vary greatly in colour, shape and size, and the bigger the bird, the bigger the egg. Since domestication, avian species have been basically reared for eggs, meat, pleasure and research. They reproduce sexually with the spermatozoa being homogametic and carry Z-bearing chromosomes, and the blastodisk carries either Z-bearing or W-bearing chromosomes, hence, the female is heterogametic, and thus, determines the sex of the offspring. The paired testes produce spermatozoa, sex hormones and the single ovary (with a few exceptions) produces yolk bearing the blastodisk and sex hormones. Both testis and ovary are the primary sex organs involved in sexual characteristics development in avian. In avian reproduction, there must be mating for fertile egg that must be incubated to produce the young ones. At hatch, hatchling sex is identified and reared to meet the aim of the farmer.

Cyp11a2 is essential for oocyte development and spermatogonial stem cell differentiation in zebrafish

Cytochrome P45011A1, encoded by Cyp11a1, converts cholesterol to pregnenolone (P5), the first and rate-limiting step in steroidogenesis. In zebrafish, cyp11a1 is maternally expressed and cyp11a2 is considered the ortholog of Cyp11a1 in mammals. A recent study has shown that depletion of cyp11a2 resulted in steroidogenic deficiencies and the mutants developed into males with feminized secondary sexual characteristics. Here, we independently generated cyp11a2 mutants in zebrafish and showed that the mutants can develop into males and females in the juvenile stage, but finally into infertile males with defective mating behavior in the adult stage. In the developing ovaries, the cyp11a2 mutation led to stage I oocyte apoptosis and final sex reversal, which could be partially rescued by treatment with P5 but not estradiol. In the developing testes, depletion of cyp11a2 resulted in dysfunction of Sertoli cells and lack of functional Leydig cells. Spermatogonial stem cells (SSCs) in the mutant testes underwent active self-renewal but no differentiation, resulting in a high abundance of SSCs in the testis, as revealed by immunofluorescence staining with Nanos2 antibody. The high abundance and differentiation competence of SSCs in the mutant testes were verified by a novel testicular cell transplantation (TCT) method developed in this study, by transplanting mutant testicular cells into germline-depleted wild-type (WT) fish. The transplanted mutant SSCs efficiently differentiated into functional spermatids in WT hosts. Overall, our study demonstrates the functional importance of cyp11a2 in early oogenesis and differentiation of SSCs.

The Value of Urinary Gonadotropins in the Diagnosis of Central Precocious Puberty: A Meta-Analysis

Review question / Objective: Precocious puberty is defined as the onset of secondary sexual characteristics before the age of 8 years in girls and 9 years in boys. It can be differentiated into central precocious puberty (CPP) and peripheral precocious puberty, and it is more common in girls than in boys. CPP may result in a decreased final adult height, an early age at menarche, and psychological and health problems in adulthood. Gonadotropin-releasing hormone (GnRH) GnRH stimulation test has been indispensable in the diagnosis of CPP. GnRH stimulation test is not only invasive, time-consuming and expensive, but also sometimes difficult to have patients cooperate. Nocturnal urinary LH and FSH can represent gonadotropin excretion in children with normal and early puberty. And urinary sample collection and evaluation are more convenient, more acceptable, cheaper, and noninvasive. This meta-analysis aims to assess the value of first-voided urinary luteinizing hormone (LH) and the ratio of urinary luteinizing hormone and follicle-stimulating hormone (FSH) in the diagnosis of female CPP and to compare the accuracy between urinary gonadotropins and serum GnRH-stimulated gonadotropins.

Rearing of Bitterling (Rhodeus amarus) Larvae and Fry under Controlled Conditions for the Restitution of Endangered Populations

Among the several dozen European freshwater fish species, only European bitterling (Rhodeus amarus Bloch) and Rhodeus meridionalis belong to the group of ostrakophilous fish. The embryonic and larval development of the fish in this reproductive group until the time of the yolk sac resorption takes place in the gill cavity of river mussels (Anodonta sp. or Unio sp.). This paper presents the results of the European bitterling Rhodeus amarus being reared under controlled conditions. Bitterling larvae were caught together with river mussels in the natural environment and subsequently placed in a tank for behavioural observations. Bitterling larvae were seen swimming in the water within a week of placing the bivalves under controlled conditions. The bitterling larvae were 8.6 ± 0.11 mm long when they started to swim actively. The rearing was conducted in water at 20 and 26 ± 0.5 °C and lasted for 6.5 months (200 days) in both variants. Initially, the larvae were fed with live nauplii of Artemia salina and subsequently with fodder. The bitterlings in tanks with water at 26 ± 0.5 °C were 66.2 ± 3.0 mm long and weighed 3389 ± 548 mg. For comparison, bitterlings kept in water at 20 ± 0.5 °C were 64.48 ± 3.4 mm long and weighed 3242 ± 427 mg. No larval malformities or mortality were observed during the larvae and fry rearing. The bitterlings had well-developed secondary sexual characteristics and exhibited pre-spawning behaviour at the end of the rearing. This produced suitable bitterling stocking material to be used in the conservation of small or endangered populations.

Cellular Senescence in Adrenocortical Biology and Its Disorders

Cellular senescence is considered a physiological process along with aging and has recently been reported to be involved in the pathogenesis of many age-related disorders. Cellular senescence was first found in human fibroblasts and gradually explored in many other organs, including endocrine organs. The adrenal cortex is essential for the maintenance of blood volume, carbohydrate metabolism, reaction to stress and the development of sexual characteristics. Recently, the adrenal cortex was reported to harbor some obvious age-dependent features. For instance, the circulating levels of aldosterone and adrenal androgen gradually descend, whereas those of cortisol increase with aging. The detailed mechanisms have remained unknown, but cellular senescence was considered to play an essential role in age-related changes of the adrenal cortex. Recent studies have demonstrated that the senescent phenotype of zona glomerulosa (ZG) acts in association with reduced aldosterone production in both physiological and pathological aldosterone-producing cells, whereas senescent cortical-producing cells seemed not to have a suppressed cortisol-producing ability. In addition, accumulated lipofuscin formation, telomere shortening and cellular atrophy in zona reticularis cells during aging may account for the age-dependent decline in adrenal androgen levels. In adrenocortical disorders, including both aldosterone-producing adenoma (APA) and cortisol-producing adenoma (CPA), different cellular subtypes of tumor cells presented divergent senescent phenotypes, whereby compact cells in both APA and CPA harbored more senescent phenotypes than clear cells. Autonomous cortisol production from CPA reinforced a local cellular senescence that was more severe than that in APA. Adrenocortical carcinoma (ACC) was also reported to harbor oncogene-induced senescence, which compensatorily follows carcinogenesis and tumor progress. Adrenocortical steroids can induce not only a local senescence but also a periphery senescence in many other tissues. Therefore, herein, we systemically review the recent advances related to cellular senescence in adrenocortical biology and its associated disorders.

Reproductive developmental dynamics during the early and intermediate prepuberal periods in Nelore breed (Bos indicus) calves

The demand for calves as oocyte donors for in vitro embryo production is growing. However, Bos indicus have a late puberty, and some aspects of the reproductive physiology during the prepubertal period remain unclear. We characterized endocrine and morpho-functional reproductive features in Nelore calves (n=8) at 2- 5 (early prepubertal period, EPP) and from 8-11 months old (mo., intermediate prepubertal period, IPP). The calves’ ovaries and uterus were B-mode transrectal ultrasonography examined, and blood samples were collected every second week. The antral follicles number and size, and ovarian and uterine horn diameters, were recorded, and plasma FSH and LH concentrations were measured (RIA). Non-pregnant, non-lactating cyclic Nelore cows (n=8) were used as controls for endocrine endpoints. Somatic development was monitored by monthly weighing, and 3D scanning of the rump area. The somatic and endocrine endpoints were compared within and between EPP and IPP, and between each period and control cows. Associations were determined by the Spearman correlation method, and the developmental rates were determined by non-linear regression. All morphological endpoints, except antral follicle count, increased (P < 0.001) from the EPP to the IPP. However, within each period differences occurred only at EPP. During the EPP LH and FSH plasma concentrations were similar (P > 0.05), whereas during the IPP LH was lower (P < 0.05) and FSH was higher (P < 0.001) than control cows. The EPP calves showed moderate to high positive correlations among ovarian, uterine, and somatic endpoints. Conversely, the IPP such correlations were mostly weak. In summary, distinct ovarian activity and development patterns of primary and secondary sexual characteristics occurred in Nelore calves at 2- 5 mo compared to 8-11 mo.

New and consolidated therapeutic options for pubertal induction in hypogonadism: in-depth review of the literature

Delayed puberty (DP) defines a retardation of onset/progression of sexual maturation beyond the expected age due to either a lack/delay of the hypothalamo-pituitary-gonadal (HPG) axis activation or a gonadal failure. DP usually gives rise to concern and uncertainty in patients and their families, potentially affecting their immediate psychosocial well-being and also creating longer-term psychosexual sequelae. The most frequent form of DP in younger teenagers is self-limiting and may not need any intervention. Conversely, DP due to hypogonadism requires prompt and specific treatment that we summarize in this review. Hormone therapy primarily targets genital maturation, development of secondary sexual characteristics and the achievement of target height in line with genetic potential, but other key standards of care include body composition and bone mass. Finally, pubertal induction should promote psychosexual development and mitigate both short- and long-term impairments comprising low self-esteem, social withdrawal, depression and psychosexual difficulties. Different therapeutic options for pubertal induction have been described for both males and females but we lack the necessary larger randomized trials to define the best approaches for both sexes. We provide an in-depth and updated literature review regarding therapeutic options for inducing puberty in males and females, particularly focusing on recent therapeutic refinements that better encompass the heterogeneity of this population, and underlining key differences in therapeutic timing and goals. We also highlight persistent shortcomings in clinical practice, wherein strategies directed at “the child with delayed puberty of uncertain aetiology” risk being misapplied to older adolescents likely to have permanent hypogonadism.

Sex/Gender Attribution: When the Penis Makes the Difference

The present study aimed to replicate Kessler and McKenna’s (1978) ethnomethodological study that investigated how an individual attributes gender to a person. By administering figures depicted on overlays (Overlay Study), Kessler and McKenna found that the penis more than the vulva and the male sexual characteristics more than the female ones were significantly more salient in the gender attribution process. From all this, their adage is: “See someone as female only when you cannot see them as male.” Taking as a model Kessler and McKenna’s Overlay Study, we administered to 592 adults 120 new digital stimuli elaborated on realistic frontal images of human nudes to verify if the previously obtained results would be confirmed by using more realistic images. We found that the participants attributed male gender 86% of the time when the penis was shown, but only attributed female gender 67% of the time when the vulva was shown. All findings had strong statistical significance, confirming the findings of the Overlay Study that the penis makes the difference in gender recognition. Beyond an ethnomethodological approach, we have interpreted and discussed our results from the outlook of evolutionary and cognitive psychology and cognitive neuroscience, concluding that the cultural stereotypes and prejudices that affect gender attribution might not just be a mere cultural product, but rather the consequence of evolved cognitive biases.

Intersexual and intrasexual selection for neck musculature in men: Attractiveness, dominance, and actual fighting success

Countless organisms are equipped with physiological armor that reduce damage from opponents. Because humans have sustained a long evolutionary history of hand-to-hand combat, selection would have been placed on morphological structures which reduce rotational acceleration to the head and increase the likelihood of victory. Grounded in over 60 years of sports performance theory and recent theoretical work in evolutionary biology, geometric morphometric analyses revealed that larger neck musculature in professional combatants (N = 715) was associated with greater real-world fighting success, after for adjusting for allometry (Study 1). Because sexual dimorphism emerges from selection on morphological structures that improve men’s fighting success, we then discovered that the human neck is the most sexually dimorphic feature of human anatomy when compared to 91 other anatomical features (N = 6,068; Study 2). This male-biased sexual dimorphism held after controlling for these 91 allometric measurements, and held across every world region (Africa, Asia, Europe, Oceania, and North, Central, and South America). Because human psychological systems consequently evolved to attend to men’s secondary sexual characteristics, we discovered that men (N = 564 stimuli) with larger neck musculature (Study 3: geometric morphometrics; Study 4: physiological neck strength; Study 5: photorealistic stimuli) are rated (N = 772 raters) as stronger, more masculine, and higher in fighting ability and short-term attractiveness, after accounting for allometry. Combined, our research introduced a new secondary sexual characteristic to the biological, anthropological, and psychological sciences: the human neck.

Kallmann Syndrome and X-linked Ichthyosis Caused by Translocation Between Chromosomes X and Y: A Case Report

Background: Xp22.3 region is characterized by low frequency of interspersed repeats and low GC content. Several clinically important genes including ANOS1 (KAL1) reside in this region. This gene was first identified due to translocation between chromosomes X and Y in a patient with Kallmann syndrome. Case Presentation: A 20 year old male presented with complaints of delayed secondary sexual characteristics, impaired sense of smell, and poor scholastic performance. On examination, he had short stature (151 cm; <3rd centile). His sexual maturity corresponded to Tanner stage 3. Stretched penile length was 3.6 cm (<3rd centile). Right testis was undescended with low left testicular volume (12 ml). There was mild ichthyosis over abdomen and back. He had hyposmia, hoarse voice, and synkinesia. Investigations were suggestive of hypogonadotrophic hypogonadism. Karyotype revealed an extra chromosomal material on p arm of chromosome X (46,Xp+,Y). On cytogenetic microarray, deletion of 8.3 Mb on Xp22.33 region and duplication of 12.8 Mb on Yq11.22 region were identified. The breakpoint on X chromosome resulted in deletion of exons 7-14 of ANOS1 gene and complete STS, NLGN4X, ARSL (ARSE), SHOX, and VCX genes. Conclusion: Patients diagnosed with Kallmann syndrome should receive careful clinical evaluation to detect presence of a contiguous gene syndrome.