Perinuclear theca during spermatozoa maturation leading to fertilization

Abstract

Mammalian spermatozoa acquire the capacity to fertilize the ovum and display motility during their passage through the epididymis. At the same time, they undergo changes in metabolic patterns, enzymatic activities, ability to bind to zona pellucida surface, and electrophoretic properties and, furthermore, stabilization of some sperm structures by the establishment of disulphide linkages takes place in several sperm structures. The cytoplasmic perinuclear theca (PT) is a unique extranuclear cytoskeletal element that surrounds the nucleus, which is proposed to be a structural scaffold to the sperm nucleus. The purpose of this review is to describe PT changes related to epididymal sperm maturation. We will focus mainly on the protein components of the PT of eutherian mammalian spermatozoa and on quantitative protein changes during sperm maturation. The protein constituents of the PT have not been completely defined and most of them are different from the cytoskeletal proteins of somatic cells. However, they are proteins with cytoskeletal features. The morphologic changes reported for PT and the proposed functions of PT are discussed.

Novel Aspect of Perinuclear Theca Assembly Revealed by Immunolocalization of Non-Nuclear Somatic Histones During Bovine Spermiogenesis1

“…The stages of the cycle of bovine seminiferous epithelium (I-XII) and steps in spermiogenesis (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) in testicular sections were identified according to Berndston and Desjardins [32] for light microscopy (LM) and Barth and Oko [33] for EM analysis. The 14 steps of bovine spermiogenesis were defined according to Barth and Oko [33] for EM analysis.…”

“…Morphological studies indicate that PT assembly occurs in two stages: First, the emergence of the SL occurs in concert with the acrosome development in early spermiogenesis; second, the PAS is assembled during the caudal descent of the manchette in midspermiogenesis [1]. To date, a range of both traditional and nontraditional cytoskeletal proteins have been found to reside within the PT, having a particular subcellular distribution within these distinct regions.…”

“…To date, a range of both traditional and nontraditional cytoskeletal proteins have been found to reside within the PT, having a particular subcellular distribution within these distinct regions. Numerous PT proteins typically accumulate in the SL by the onset of spermatid elongation [1,2], while some initially localize to the membranes of proacrosomic vesicles in round spermatids [2,3]. With the exception of SubH2Bv, a histone H2B-like variant retained within the SL [3], many PT proteins become associated to the PAS in late elongated spermatids [2].…”

“…The PT is a condensed cy- tosolic element that encases the entire sperm nucleus except at the base, and consists of two morphologically distinct regions, termed the subacrosomal layer (SL) and the postacrosomal sheath (PAS) (reviewed in [1]). Though implicated in various aspects of spermiogenesis, such as acrosome-nuclear docking [2,3] and sperm-head shaping [4,5], the PT has recently gained much attention for its role in egg activation during fertilization (reviewed in [6]).…”

Identification and characterization of ERp29 in rat spermatozoa during epididymal transit

“…nucleus, acrosome, perinuclear theca, fibrous sheath, cytoplasmic droplet, and, especially, plasma membrane (Westhoff & Kamp 1997, Cooper & Yeung 2003, Mujica et al 2003, Olson et al 2003). However, results from different laboratories, using a variety of methods, are quite diverse in their findings on protein variations in the spermatozoa during epididymal transit (Dacheux et al 2003, 2005, Saez et al 2003, Toshimori 2003, Gatti et al 2004.…”