The organization and the histological characteristics of Leptodactylus chaquensis testis throughout the reproductive cycle were analyzed in the presented study. Gonads of adult males, processed with routine techniques for optical microscopy, revealed that during the reproductive period the seminiferous tubules were characterized by presentation of a large number of cysts, germ cells at the same maturation stage supported by Sertoli cells. All the germ line cells were also present in the postreproductive period and maintained their morphological characteristics. Primary spermatogonia were large-sized cells found isolated or in small groups. The rest of the cells of the germ line formed cysts. Secondary spermatogonia showed morphological characteristics similar to their predecessors, although they were smaller. Primary and secondary spermatocytes showed images of the different stages of the first and second meiotic division respectively. One finding was the presence of intercytoplasmic bridges between the secondary spermatocytes. Primary spermatids were rounded cells with an acrosomal vesicle associated with the nucleus and had cysts that were characterized by large intercellular spaces. Secondary spermatids were elongated cells with a well defined acrosome, which in the spermatozoa had the shape of an arrowhead. Another peculiar characteristic of this species was the fusion of the walls of the seminiferous tubule with the efferent duct that formed a path for spermatozoa during spermiation. The presence in the seminiferous tubules of all stages of the spermatogenic line during the two periods of the cycle studied indicated that Leptodactylus chaquensis had a potentially continuous reproductive cycle.

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The endocrine regulation of the mucosa of the oviductal pars convoluta was analyzed by ultrastructural studies demonstrating that ovariectomy, together with a decrease in ovarian steroids circulating levels, caused a marked regression in this portion of Bufo arenarum oviduct. Twenty-five days after ovariectomy, a decrease in the depth of the epithelial and glandular layers was observed due to the notable loss of secretory cells, whose number was clearly smaller than in nonovariectomized females. The remaining secretory cells showed involution signs, with few secretory granules in their cytoplasm, little endoplasmic reticulum near poorly developed Golgi complexes and a large amount of lipid droplets. Cells in an advanced autolysis state were found in the lumen. These characteristics evidence a nonfunctional state of the pars convoluta. Treatment with 5alpha-dihydrotestosterone (DHT) completely reversed the ovariectomy effect, inducing pars convoluta growths and restoring the characteristics of epithelial and glandular secretory cells in the whole pars convoluta, with micrographs similar to the control. These same effects were observed after treatment with estradiol-17beta (E2), progesterone (P) o E(2)+P in the glandular layer of the whole pars convoluta, but only in the epithelial layer of the most anterior region of this duct. In the secretory cells of other segments these treatments induced the formation of granules of high electron density and homogeneous aspect. Each steroid had a particular effect on the pars convoluta. Although E2 and DHT induced the development of the organoids involved in the proteins biosynthesis, P and DHT acted as secretagogues.