The development of the sexually indifferent gonad in the prosimian, <i>Galago crassicaudatus crassicaudatus</i>

Yoshinaga, Kazuya; Hess, David L.; Hendrickx, Andrew G.; Zamboni, Luciano

doi:10.1002/aja.1001810110

Cited by 30 publications

(17 citation statements)

References 59 publications

(78 reference statements)

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“…A continuous contribution of mesonephric cells to the indifferent gonad contrasts with the results of Yoshinaga et al (1988) on this subject in a primate, the prosimian Galago. Despite the fact that the same group, when studying the corresponding process in other mammalian species (mouse: Upadhyay et al, 1979Upadhyay et al, ,1981sheep: Zamboni et al, 1979sheep: Zamboni et al, ,1981Zamboni and Upadhyay, 1982) confirmed the positive role of the mesonephros in testicular and ovarian development, in this primate these authors ascribe the formation of the indifferent gonadal blastema to the proliferative process of the coelomic epithelium.…”

Section: Role Of Mesonephric Corpuscles In Contributingmentioning

confidence: 72%

Fine structural characteristics of testicular cord formation in the developing rabbit gonad

Wartenberg

Kinsky

Viebahn

et al. 1991

J. Elec. Microsc. Tech.

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This paper presents morphological (light- and electron-microscopical) evidence for the role of the mesonephros in contributing cells to the differentiating indifferent gonad and, after sexual differentiation, to the testis. A continuous process is revealed during which segregation of cells occurs from the developing and regressing mesonephros. Additionally, the complementary role of the coelomic epithelium in gonadal ridge and testis formation is demonstrated. The differentiation of testicular cords, their remodelling from a primary reticulum, and the composition and further change of the cellular content during the period after sexual differentiation is described using a computer-aided three-dimensional reconstruction system. Apart from these morphogenetic events, cytodifferentiation in the somatic cells of the indifferent gonad and of the early differentiated testis is demonstrated using indirect immunofluorescence in combination with monoclonal antibodies to the intermediate filament proteins keratin 8 and 18 and vimentin. The immunohistochemical results show that different forms of cytodifferentiation coexist among the somatic cells present in the indifferent gonad and in the testis early after sexual differentiation.

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Section: Role Of Mesonephric Corpuscles In Contributingmentioning

confidence: 72%

Fine structural characteristics of testicular cord formation in the developing rabbit gonad

Wartenberg

Kinsky

Viebahn

et al. 1991

J. Elec. Microsc. Tech.

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“…In contrast, chick PGC contains a large amount of glycogen granules in the cytoplasm, which is the most prominent characteristic of the cells (Meyer, 1964;Fujimoto et al, 1976). This high content of the glycogen in PGC cytoplasm has also been demonstrated in some mammalian species, such as human (Fujimoto et al, 1977) and a prosimian (Yoshinaga et al, 1988), for example. It is, however, unclear why there are species-specific differences in the persistence of glycogen reserves.…”

Section: Discussionmentioning

confidence: 79%

Ultrastructural characteristics of primordial germ cells in the quail embryo

1993

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An avian species, the quail has become a desirable animal model in experimental embryology and reproductive biology. To understand the ultrastructural characteristics of primordial germ cells (PGC) of this species, we studied PGC in the Japanese quail (Coturnix coturnix japonica) embryo at various developmental stages from their appearance in the germinal crescent through migration to settlement in the gonadal ridges by means of electron microscopy. The results were compared with those of another well-known avian species, the chick. Several ultrastructural characteristics of quail PGC not described previously in chick PGC were observed as follows: 1) No glycogen particles were detected in the cytoplasm at any stage examined. 2) Electron-dense and membrane-bounded granules were found in the PGC cytoplasm during the sexually indifferent gonadal stages. 3) Quail PGC were characterized by a prominent nucleolus associated with condensed chromatin (heterochromatin), and the developmental changes of the nucleus were noted; the nucleolus initially appeared as a compact mass at the germinal crescent stage and became dispersed at later stages during the colonization of the gonadal ridges. These findings suggest several physiological and functional differences in the cell cycle between these two avian species. This is the first report describing detailed ultrastructural characteristics of PGC in the quail embryo.

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“…In ruminants, the somatic elements of the gonads are also mesonephric in origin but they differentiate from the cellular elements of the glomerulus of the "giant nephron," (12,13) a singular structure which is a peculiarity of the mesonephroi of these animals. In primates, instead, the somatic cells of the gonad are of mesothelial origin (9) and do derive from the coelomic mesothelial cells lining the surface of the genital folds as originally reported by several classic investigators; in primates, thus, the mesonephros shares in the organization of the gonads only with regard to the assembly of the gonadal rete and, in the male, of the more distal segments of the testicular excretory system (vide infra), whereas in rodents and ruminants, it participates in the organization of both the gonad and its excretory pathways. In a recent article (9), we explained these differences on the basis of the differences that exist among species concerning not only degrees of organization and functionality of their mesonephroi, but also the relationship between the time when the PGCs arrive in the gonadal folds and stages of mesonephric development or involution.…”

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confidence: 98%

Overview of Embryological and Fetal Development of the Ovary and Testis

Zamboni

1989

Growth Factors and the Ovary

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2The events that take place in the urogenital region during mammalian embryonal and fetal life represent ideal subjects of study for those interested in cellular differentiation and organogenesis. Within a short period of time, from a few hours in species with short gestational periods to no more than several days in those with longer ones, the urogenital region witnesses the arrival of the primordial germ cells (PGCs), their colonization of the genital folds, and the concomitant "activation" of the cells preexisting in the area, major phenomena that culminate in the development of a sexually indifferent gonad. The subsequent differentiation of the latter into a testis or an ovary is accompanied by the maturation of the PGCs into germinal elements with distinct sexually dimorphic characteristics, the development of a complex system of blood vessels and nerves, the differentiation of interstitial elements with important endocrine functions, the sexually dimorphic involution/transformation of the mesonephros, and the organization of the metanephros as the definitive excretory organ.Of these phenomena, the migration of the PGCs to, and their colonization of, the genital ridges, the origin of the somatic cells which at first contribute to the formation of the blastema of the sexually indifferent gonad together with the germinal cells and later differentiate into the definitive testicular and ovarian sustentacular elements, and the sexually dimorphic patterns of male and female germinal cell differentiation with emphasis on the time of initiation of meiosis are those that have been most intensively studied. While many of the issues related to the evolution of these phenomena and their regulatory mechanisms have been clarified, others remain unsettled and require further study.In all mammals, onset of gonadal development is heralded by the arrival of the PGCs to the gonadal folds following a migratory journey that initiates in the yolk sac and takes the germ cells through the primitive intestine and its mesentery. In mammals, PGC migration is exclusively extravascular, sporadic reports to the contrary (1, for example) being based on the erroneous interpretation, mostly due to similarities in size and overall appearance, of circulating megakaryocytes as primordial germinal cells. It has been firmly established that the PGCs cover the distance separating the yolk sac from the gonadal folds primarily by

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The development of the sexually indifferent gonad in the prosimian, Galago crassicaudatus crassicaudatus

Cited by 30 publications

References 59 publications

Fine structural characteristics of testicular cord formation in the developing rabbit gonad

Fine structural characteristics of testicular cord formation in the developing rabbit gonad

Ultrastructural characteristics of primordial germ cells in the quail embryo

Overview of Embryological and Fetal Development of the Ovary and Testis

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