Subcellular distribution of calcium during spermatogenesis of zebrafish, Danio rerio

Abstract

Calcium plays a variety of vital regulatory functions in many physiological and biochemical events in the cell. The aim of this study was to describe the ultrastructural distribution of calcium during different developmental stages of spermatogenesis in a model organism, the zebrafish (Danio rerio), using a combined oxalate-pyroantimonate technique. Samples were treated by potassium oxalate and potassium pyroantimonate during two fixation stages and examined using transmission electron microscopy to detect electron dense intracellular calcium. The subcellular distribution of intracellular calcium was characterized in spermatogonium, spermatocyte, spermatid, and spermatozoon stages. The area which is covered by intracellular calcium in different stages was quantified and compared using software. Isolated calcium deposits were mainly detectable in the cytoplasm and the nucleus of the spermatogonium and spermatocyte. In the spermatid, calcium was partially localized in the cytoplasm as isolated deposits. However, most calcium was transformed from isolated deposits into an unbound pool (free calcium) within the nucleus of the spermatid and the spermatozoon. Interestingly, in the spermatozoon, calcium was mainly localized in a form of an unbound pool which was detectable as an electron-dense mass within the nucleus. Also, sporadic calcium deposits were scattered in the midpiece and flagellum. The proportional area which was covered by intracellular calcium increased significantly from early to late stages of spermatogenesis. The extent of the area which was covered by intracellular calcium in the spermatozoon was the highest compared to earlier stages. Calcium deposits were also observed in the somatic cells (Sertoli, myoid, Leydig) of zebrafish testis. The notable changes in the distribution of intracellular calcium of germ cells during different developmental stages of zebrafish spermatogenesis suggest its different homeostasis and physiological functions during the process of male gamete development.

Effects of Calcium Nanoparticles on Male Rat Fertility and Sperm Function

“…The main objective of this study was to evaluate the effects of calcium deprivation and calcium (Nano particles and commercial) administration on male rat reproductive functions. Multiple investigations have shown that Ca 2+ plays a major role in sperm control and fertilization events [41,42]. Our results revealed a significant decrease in serum calcium, testosterone hormone and ABP levels in Ca 2+ -deficient group as a consequence of receiving purified rat protein diet deficient in calcium for 64 days, on the other hand it revealed a significant increase in their levels in serum of Nano and commercial calcium administered male rats.…”

Determination of annual reproductive cycle in male sterlet, Acipenser ruthenus using histology and ultrasound imaging

“…In studies on annual gonadal cycle of fish, it is crucial to examine gonadal cycle and spawning pattern (Tan-Fermin et al, 1997;Manosroi et al, 2003;Golpour et al, . 2017Niksirat et al, 2017).…”

IP3R Channels in Male Reproduction

“…Studies have shown that calcium signaling is also involved in spermatogenesis, sperm function, and fertilization, essential processes for male reproduction [1]. Calcium ions are stored in spermatogenic cells at various developmental stages, and also in Leydig and Sertoli cells [2]. The concentration of calcium in spermatogenic cells gradually increases from the early to late stages of spermatogenesis (spermatogonia < spermatocytes < spermatids < spermatozoa), and the concentration of calcium ions in seminiferous tubules also varies in different sections [2,3].…”

“…Calcium ions are stored in spermatogenic cells at various developmental stages, and also in Leydig and Sertoli cells [2]. The concentration of calcium in spermatogenic cells gradually increases from the early to late stages of spermatogenesis (spermatogonia < spermatocytes < spermatids < spermatozoa), and the concentration of calcium ions in seminiferous tubules also varies in different sections [2,3]. Calcium signaling in Leydig cells regulates the production of steroids through nuclear receptors and emergency response proteins mediated by a transcription cascade [4].…”