Sertoli–germ cell junctions in the testis: a review of recent data

Abstract

Spermatogenesis is a process that involves an array of cellular and biochemical events, collectively culminating in the formation of haploid spermatids from diploid precursor cells known as spermatogonia. As germ cells differentiate from spermatogonia into elongated spermatids, they also progressively migrate across the entire length of the seminiferous epithelium until they reach the luminal edge in anticipation of spermiation at late stage VIII of spermatogenesis. At the same time, these germ cells must maintain stable attachment with Sertoli cells via testis-unique intermediate filament-(i.e. desmosome-like junctions) and actin-(i.e. ectoplasmic specializations, ESs) based cell junctions to prevent sloughing of immature germ cells from the seminiferous epithelium, which may result in infertility. In essence, both desmosome-like junctions and basal ESs are known to coexist between Sertoli cells at the level of the blood -testis barrier where they cofunction with the well-studied tight junction in maintaining the immunological barrier. However, the type of anchoring device that is present between Sertoli and germ cells depends on the developmental stage of the germ cell, i.e. desmosome-like junctions are present between Sertoli and germ cells up to, but not including, step 8 spermatids after which this junction type is replaced by the apical ES. While little is known about the biology of the desmosome-like junction in the testis, we have a relatively good understanding of the molecular architecture and the regulation of the ES. Here, we discuss recent findings relating to these two junction types in the testis, highlighting prospective areas that should be investigated in future studies.

Mono-butyl phthalate-induced mouse testis injury is associated with oxidative stress and down-regulated expression of <i>Sox9</i> and <i>Dazl </i>

“…Normal Sertoli cell differentiation is indispensable for testis formation. Sertoli cells provide critical factors necessary for spermatogenesis, including providing nutritional and structural support, creating an impermeable and immunological bar- rier, participating in germ cell movement and spermiation (Kopera et al, 2010). The results of the present study indicated that down-regulated expression of Sox9 mRNA damaged the Sertoli cell differentiation, which would contribute to the loss of spermatogenesis.…”

Autophagy is required for ectoplasmic specialization assembly in sertoli cells

“…The CDH2-CTNNB1 complexes function in apical ES stabilization, while JAM3 functions in spermatid polarization and positioning. 7 The apical ES has a key role in spermatogenesis, and structurally abnormal or absent apical ES has been associated with inappropriate release of spermatids or spermatids abnormalities. 52,53 Some early studies indicated that the apical ES participates in sperm head shaping.…”

“…6,7 Besides the tight junctions and gap junctions that are also present in other epithelia, the seminiferous epithelium exhibits testis-unique anchoring junctions, including the ectoplasmic specialization (ES) and the desmosome-like junction. 6,8 The ES is an actin microfilament-rich anchoring device using F-actin for attachment 9 at the SertoliSertoli cell interface known as the basal ES (bES), which together with the tight junctions, gap junctions and the desmosome-like junction create the blood-testis barrier (BTB).…”

“…[9][10][11][12] The apical compartment of the Sertoli cell-elongating spermatid interface, called apical ES (aES), interacts with the acrosome region of the elongating spermatid and mechanically grasps the head of spermatids to undergo rapid elongation and maturation. 6,7,9,11,13 The main roles of the apical ES include shaping the spermatid head, facilitating spermatid cell movement, orienting the elongated spermatid and releasing mature spermatozoa during spermiation. 10,13 In the Sertoli cell-elongating spermatid interface, the apical ES consists of a narrow layer of hexagonally packed, parallel actin bundles sandwiched between the Sertoli cell plasma membrane and an endoplasmic reticulum (ER) cistern on the Sertoli cell side of the plasma membrane.…”

Metabolic Cooperation in Testis as a Pharmacological Target: From Disease to Contraception

“…The junctions established between SCs and germ cells are of two types: desmosome-like junctions and ectoplasmic specializations (ES). These junctions mediate adhesion and are essential for spermatogenesis [31]. The association between SCs and germ cells is of such relevance that each particular association is referred as a stage of the seminiferous epithelium cycle.…”