Stages of the cycle of the seminiferous epithelium of the Viscacha (Lagostomus maximus maximus)

Abstract

The adult male viscacha (Lagostomus maximus maximus) is a seasonal rodent. It exhibits a short period of testicular regression with partial arrest of spermatogenesis during winter (July-August). The present study provides the first description of the viscacha spermatogenic cycle during the period of maximum gonadal activity (summer-autumn).The testes were processed by using conventional techniques of light and electron microscopy. One-micrometer-thick sections stained with toluidine blue were used to clearly define the different cell associations.Spermatogenesis in this rodent is well organized and synchronized and has been divided into nine stages. The present classification is based on the morphogenesis of the acrosomal system (stages I-V) and the degree of elongation and condensation of the heads of the differentiating spermatids (stages VI-IX). Stage I is principally defined by round spermatids with a well-developed, juxtanuclear Golgi complex and without acrosomal components that are visible under the light microscope. Sperm release from the viscacha seminiferous epithelium occurs either in late stage III or in early stage IV. Stage IX is characterized by diplotene spermatocytes, figures of meiosis I or II, and secondary spermatocytes. Anat.

Ultrastructural and morphometric study of the sertoli cell of the viscacha (Lagostomus maximus maximus) during the annual reproductive cycle

“…The identification of various germ cells and stages of the viscacha spermatogenic cycle was based on the description provided by us in active testes (Muñ oz et al, 1998). The identification of various germ cells and stages of the viscacha spermatogenic cycle was based on the description provided by us in active testes (Muñ oz et al, 1998).…”

“…The testicular regression period during the short days of winter (July-August) ranges from a substantial reduction in the population of spermatids and mature spermatozoa in some animals to an almost complete arrest of spermatogenesis in others. Testicular restoration during spring is followed by a period of maximum activity during the long days of summer and autumn (Fuentes et al, 1991(Fuentes et al, , 1993Muñ oz et al, 1997Muñ oz et al, , 1998. Specifically, testicular concentrations of LH, FSH, and prolactin (Prl) receptors are minimal in the regressed animals (Fuentes et al, 1993).…”

Morphological study of the prostate gland in viscacha (Lagostomus maximus maximus) during periods of maximal and minimal reproductive activity

“…The reproductive cycle of the adult male viscacha in its habitat is mainly characterized by higher gonadal activity in summer and lower gonadal activity during winter. Morphological changes have been reported in testes (Muñoz et al 1997(Muñoz et al , 1998(Muñoz et al , 2001, epididymis (Fuentes et al, 1991;Aguilera-Merlo et al, 2005a, and spermatozoids of viscacha (Aguilera-Merlo et al, 2005b). Accessory glands of this animal, the prostate gland, seminal vesicles, coagulating gland, and bulbourethral glands were described by Chaves et al (2011), but morphological variations of the viscacha's prostate in relation to the reproductive cycle have not been studied, nor have the accessory glands in the reproductive system of male wild animals with cyclical reproduction.…”

Unusual germ cell organization in the seminiferous epithelium of a murid rodent from southern Asia, the greater bandicoot rat,Bandicota Indica

“…Cell associations within the testes have been described for various rodent species besides common laboratory mice and rats, including hamsters (Clermont & Trott, 1969; Oud & de Rooij, 1977), prairie voles (Schuler & Gier, 1976), field voles (Grocock & Clarke, 1975, 1976), bank voles (Grocock & Clarke, 1976), grey squirrels (Tait & Johnson, 1982), mole rats (Redi et al. , 1986), Asian gerbils (Bilaspuri & Kaur, 1994), viscachas (Munoz et al. , 1998), capybaras (Paula et al.…”

“…Cell associations within the testes have been described for various rodent species besides common laboratory mice and rats, including hamsters (Clermont & Trott, 1969;Oud & de Rooij, 1977), prairie voles (Schuler & Gier, 1976), field voles (Grocock & Clarke, 1975, bank voles (Grocock & Clarke, 1976), grey squirrels (Tait & Johnson, 1982), mole rats (Redi et al, 1986), Asian gerbils (Bilaspuri & Kaur, 1994), viscachas (Munoz et al, 1998), capybaras (Paula et al, 1999), lesser bandicoot rats (Sinha Hikim et al, 1985), plains rats (Peirce & Breed, 1987) and hopping mice (Peirce & Breed, 1987). In all of these species, with the exception of the hopping mouse Notomys alexis (Peirce & Breed, 1987), a similar germ cell organization to that of the laboratory rat and mouse was found to occur.…”