Early gonadal development and sexual differentiation in muskellunge (Esox masquinongy)

1997 ◽  
Vol 75 (8) ◽  
pp. 1262-1269 ◽  
Author(s):  
Feng Lin ◽  
Konrad Dabrowski ◽  
Lucy P. M. Timmermans

Primordial germ cells (PGCs) were first identified in muskellunge (Esox masquinongy) of 14 mm total length (TL) 3 weeks post fertilization. At 32 mm TL, gonad strings were complete and formed a typical gonad shape in cross section. Blood vessels were first found in the gonads with Crossmon staining at 46 mm TL. Some of the PGCs underwent mitotic division at this stage. The ovarian sac started to develop in a fish of 82 mm TL, while the germ cells were still considered to be undifferentiated. In a fish of 138 mm TL, female gonads could be clearly identified from the ovarian sac and groups of oogonia, whereas in another type of gonad, the morphology of undifferentiated gonads was maintained. Germ cells became numerous in both sexes at 211 mm TL. Female gonads contained lobes with germ cells, including oogonia, early-prophase oocytes, and large oocytes. Spermatogonia and cells undergoing mitosis were observed in the testis. Ovaries in a fish of 250 mm TL were at the early stage of perinucleolus (early diplotene). Our observations indicate that in muskellunge (i) the PGCs remained in a resting state for up to 8 weeks post fertilization, (ii) gametogenesis occurred earlier in females than in males, (iii) the gonads developed from an undifferentiated stage directly into an ovary or testis, and (iv) the somatic elements in the gonads differentiated prior to the germ cells.

2016 ◽  
Vol 28 (2) ◽  
pp. 164
Author(s):  
F. Oliveira ◽  
A. Santos ◽  
A. A. Neto

Sexual differentiation in mammals is an event that presents many variations between species. Because it is related to hormonal function, any imbalance in the androgens and estrogens production can lead to malformations. Because sexual differentiation occurs in different ways among various animals, the recognition of their peculiarities becomes important in order to correct reproductive handling in different species. Considering that the guinea pig is commonly used as an experimental model in the reproductive area, the goal of this work was to perform a morphological description of gonad differentiation of the male guinea pig during embryonic development. In total, 11 conceptuses with ages 25 (n = 3), 30 (n = 2), 40 (n = 2), 50 (n = 2), and 65 (n = 2) days were used for light microscopy processing. The embryos at 25 days were processed completely. For the others, the gonads were dissected. The samples were dehydrated in alcohol, embedded in paraffin, and 5-µm sections were stained with hematoxylin-eosin. In the guinea pig gonad at 25 days gestation, there was a presence of gonadal cords, formed by condensation of somatic cells, which is characteristic of an undifferentiated gonad. In addition, we observed the presence of mesonephric and paramesonephric ducts in different embryos, indicating that other genital system organs were not formed. For the 30 days of development of guinea pigs, we observed that gonadal cords were differentiated in testicular cords by invasion of mesenchymal and endothelial cells, and also composed of Sertoli cells and primordial germ cells. These cords were among a large amount of testicular mesenchyme at the 40-day group. With 50- and 65-day development samples, the gonad was completely differentiated into testicle, with the presence of spermatogonia and Sertoli cells in the seminiferous tubules, and a large amount of interstitial Leydig cells around the tubules. We conclude that gonadal differentiation in guinea pig males occurs around the middle of pregnancy, between 25 and 30 days and that, before the end of the pregnancy, at 50 days, the testicle presents morphology similar to that found in the postnatal period.


Development ◽  
1985 ◽  
Vol 87 (1) ◽  
pp. 87-97
Author(s):  
Massimo De Felici ◽  
Gregorio Siracusa

The adhesiveness of female and male mouse primordial germ cells (PGCs) to somatic cell monolayers of various origin has been studied in the definite conditions of an in vitro system. PGCs were isolated from the gonads of embryos of various post coital ages according to the method of De Felici & McLaren (1982), and seeded on the cell monolayers. PGCs from 12·5 to 15·5 days post coitum (dpc) embryos specifically adhered to Sertoli and follicular cells obtained from adult gonads. The percentage of female PGCs which adhered to follicular cell monolayers was significantly higher than that of male PGCs. No significant adhesion was seen between PGCs and somatic cell monolayers obtained from various embryonic and adult tissues. The results obtained indicate that the simple in vitro assay described in the present paper might help to characterize the cellular interactions between somatic and germ cells during gonadal development.


1932 ◽  
Vol s2-75 (298) ◽  
pp. 251-282
Author(s):  
MARGARET TRIBE ◽  
F.W. ROGERS BRAMBELL

1. The primordial germ-cells of Sphenodon originate in the yolk-sac endoderm of the area opaca all round the embiyo, but chiefly in a crescentic area in front of it. 2. They differentiate first at a very early stage of development before the differentiation of the medullary plate. 3. The primordial germ-cells are characterized by their very large size, in comparison with all the other embryonal cells, and by their content of small yolk-spherules which are sub-equal in size. 4. The primordial germ-cells migrate through the yolk-sac endoderm and mesoderm, apparently by their own power of amoeboid movement. Many of them enter the blood-islands and the sinus terminalis. 5. The primordial germ-cells enter the embryo either (1) passively in the venous blood-stream, or (2) actively by migration through the extra-embryonal endoderm and splanchnic mesoderm into the lateral walls and the mesentery of the midgut groove. 6. The primordial germ-cells in the circulation reach the neighbourhood of the germinal ridges in the dorsal aorta or its branches. They then penetrate the walls of the vessels and migrate through the intervening tissues, together with those that have reached the base of the mid-gut mesentery by way of the splanchnic mesoderm and the mid-gut wall, to the germinal ridges. 7. Many primordial germ-cells get lost during their migration. This is especially true of those travelling in the blood-stream. Such aberrant primordial germ-cells are found occasionally in almost any part of the embryo,, but occur most often in the head, especially in the region of the fore-brain. They ultimately disappear. 8. The primordial germ-cells enter the forming germinal ridges before the coelomic epithelium covering them has begun to proliferate. 9. The primordial germ-cells, having reached the germinal ridges, lose their characteristic yolk-content and enter on the prophase of the heterotypic division.


Nature ◽  
2013 ◽  
Vol 495 (7440) ◽  
pp. 236-240 ◽  
Author(s):  
Shihori Yokobayashi ◽  
Ching-Yeu Liang ◽  
Hubertus Kohler ◽  
Peter Nestorov ◽  
Zichuan Liu ◽  
...  

Animals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2422
Author(s):  
Dragos Scarlet ◽  
Stephan Handschuh ◽  
Ursula Reichart ◽  
Giorgia Podico ◽  
Robyn E. Ellerbrock ◽  
...  

It was the aim of this study to characterize the development of the gonads and genital ducts in the equine fetus around the time of sexual differentiation. This included the identification and localization of the primordial germ cell population. Equine fetuses between 45 and 60 days of gestation were evaluated using a combination of micro-computed tomography scanning, immunohistochemistry, and multiplex immunofluorescence. Fetal gonads increased in size 23-fold from 45 to 60 days of gestation, and an even greater increase was observed in the metanephros volume. Signs of mesonephros atrophy were detected during this time. Tubular structures of the fetal testes were present from day 50 onwards, whereas cell clusters dominated in the fetal ovary. The genital ducts were well-differentiated and presented a lumen in all samples. No sign of mesonephric or paramesonephric duct degeneration was detected. Expression of AMH was strong in the fetal testes but absent in ovaries. Irrespective of sex, primordial germ cells selectively expressed LIN28. Migration of primordial germ cells from the mesonephros to the gonad was detected at 45 days, but not at 60 days of development. Their number and distribution within the gonad were influenced (p < 0.05) by fetal sex. Most primordial germ cells (86.8 ± 3.2% in females and 84.6 ± 4.7% in males) were characterized as pluripotent according to co-localization with CD117. However, only a very small percentage of primordial germ cells were proliferating (7.5 ± 1.7% in females and 3.2 ± 1.2% in males) based on co-localization with Ki67. It can be concluded that gonadal sexual differentiation in the horse occurs asynchronously with regard to sex but already before 45 days of gestation.


Author(s):  
Г Бадамханд ◽  
Д Самданжамц

The present study aimed to investigate correlation between testicle and body weights, cross section of seminiferous tubule and relationship between the Sertoli cells and matured sperms in stallion of Mongolian breed. It was found that there is significant difference (p<0.001) in testicle weights depending on ages of stallions (121.1 g at 36 months old age and 169.2 g at 48 months old). Changes in the body and testicle weights of stallions to be used for breeding are significantly different at two age classes. There were moderate (r=0.59) and strong (r=0.72) correlations at the ages of 36 and 48 months respectively. Both the testicle weight and diameter of seminiferous tubule increases in mutually related ways and tubule diameter was 72.6 µm and 94.8 µm at 36 and 48 months of stallions age respectively. Sertoli cells play key role in production of sperms from primordial germ cells in the testicle. Interrelationship between Sertol cells and mature sperms in seminiferous tubule is moderate (R2=0.316) and satisfactory (R²=0.445) correlations at 36 and 48 months of ages and it demonstrates differences between the ages are stable.


Reproduction ◽  
2020 ◽  
Author(s):  
Delia Alba Soto ◽  
Pablo Juan Ross

The germ cell lineage ensures the creation of new individuals and perpetuates the genetic information across generations. Primordial germ cells are pioneers of gametes and exist transiently during development until they differentiate into oogonia in females, or spermatogonia in males. Little is known about the molecular characteristics of primordial germ cells in cattle. By performing single-cell RNA-sequencing, quantitative real-time PCR, and immunofluorescence analyses of fetal gonads between 40 and 90 days of fetal age, we evaluated the molecular signatures of bovine germ cells at the initial stages of gonadal development. Our results indicate that at 50 days of fetal age, bovine primordial germ cells were in the early stages of development, expressing genes of early primordial germ cells, including transcriptional regulators of human germline specification (e.g. SOX17, TFAP2C, and PRDM1). Bovine and human primordial germ cells also share expression of KIT, EPCAM, ITGA6, and PDPN genes coding for membrane-bound proteins, and an asynchronous pattern of differentiation. Additionally, the expression of members of Notch, Nodal/Activin, and BMP signaling cascades in the bovine fetal ovary, suggests that these pathways are involved in the interaction between germ cells and their niche. Results of this study provide insights into the mechanisms involved in the development of bovine primordial germ cells and put in evidence similarities between the bovine and human germline.


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