Comparative testicular structure and spermatogenesis in bony fishes

Abstract

In most bony fishes, testes are paired elongated organs that are attached to the dorsal wall of the body by a mesorchium. Histological examination of teleost testes, and also in all vertebrates, shows that the testes are formed of germ cells and somatic cells, comprising the germinal and interstitial compartments. Both compartments are separated by a basement membrane. The germ cells may be spermatogonia, meiotic spermatocytes and haploid spermatids that differentiate into spermatozoa. The process of spermatogenesis includes a sequence of morphological and physiological changes of germ cells that begin with the differentiation of spermatogonia that become meiotic spermatocytes. After the second meiotic division, through a process of spermiogenesis, these differentiate into spermatozoa. Spermatogonia associate with Sertoli cells to form spermatocysts or cysts. The cyst is the unit of spermatogenic function, composed of a cohort of isogenic germ cells surrounded by encompassing Sertoli cells. The teleost testis is organized morphologically into 3 types of testis: 1) tubular testis type, present in lower bony fishes as salmonids, cyprinids and lepisosteids; 2) unrestricted spermatogonial testis type, found in neoteleosts except Atherinomorpha; and 3) restricted spermatogonial testis type, characteristic of all Atherinomorpha. The morphology of the testicular germinal epithelium changes during the annual reproductive cycle, reflecting reproductive seasonality.

Structure of the testis and spermatogenesis of the viviparous teleost Poecilia mexicana (Poeciliidae) from an active sulfur spring cave in Southern Mexico

“…Photomicrographs were taken with a digital camera Carl Zeiss AxioCam MRc5 coupled to a light microscope Carl Zeiss Axiostar Plus. Spermatogenic stages were classified as follows: A spermatogonia, B spermatogonia, primary spermatocytes, secondary spermatocytes, early spermatids, late spermatids, and spermatozoa (Uribe et al, ). For the morphometric analysis of spermatogenesis, the diameter of at least 30 cells per spermatogenic stage was measured, using a morphometric imaging software Zeiss Efficient Navigation.…”

Heterogenic Origin of Micro RNAs in Atlantic Salmon (Salmo salar) Seminal Plasma

“…Fish testis has germinal and interstitial compartments, which are composed of connective tissue and Leydig cells. The connective tissue contains fibroblasts, immunological cells, collagen fibers, myoid cells, blood vessels, and nerve fibers [32]. If seminal plasma miRNAs originated from the blood, they would likely reflect blood plasma miRNA content.…”

Hermaphroditism in the dash‐and‐dot goatfish Parupeneus barberinus

“…Tissue sections were stained in a 0·5% solution of toluidine blue in water for 15 s. Ovary sections were examined at x40 and testis sections at x100 for evidence of reproductive maturity. Ovaries were classified according to Wallace & Selman (1981) and testes according to Nagahama (1983) and Uribe et al (2014); females were considered mature with the onset of vitellogenesis or when postovulatory follicles were present and males mature when the testes contained visible spermatozoa (sperm cells with tails). Bisexual gonads were classified using the criteria of Sadovy & Shapiro (1987).…”

“…1). Testes of functional males were of the unrestricted lobular type (described in Uribe et al, 2014) and spermatogenic cells (spermatocytes and spermatids) were encapsulated by sertoli cells to form discrete spermatocysts. Eight individuals (12·9 to 22·5 cm L F ) had ovotestes (Fig.…”