Grasshopper Spermatids 



165 



^ 





t .- 



Fig. 1. Survey picture of two spermatids of the grasshopper 

 Chorthipptis. Cross-section through the anterior part of their 

 heads. Magnification 46,000. 



^, 



1 



/" 





1^ 



Fig. 2. Detail of a head with part of the "caudal sheath" and 

 the nuclear material. Magnification 103,000. 



acrosomal region consists of at least four different 

 parts, the mutual relations of which are not entirely 

 clear in this material. The acrosomal barbs have a 

 homogeneous texture. 



The nucleus, as seen in fig. 1., has a strikingly 

 regular ultrastructure. There are many uniformly 

 thick opaque filaments in a parallel arrangement 

 oriented along the long axis of the nucleus. In a 

 transverse section at the broadest part of the nucleus 

 approximately 3000 filaments, about 200 A in dia- 

 meter, have been counted. The filaments are within 

 restricted regions equally spaced in a hexagonal array 

 giving a crystal-like appearance to that region of the 

 nucleus. In longitudinal sections these filaments 

 could be followed for a distance of several microns. 

 There is no clear evidence that two adjacent filaments 

 join at their ends. Towards the basal portion of the 

 nucleus there is a general coarsening of the structure. 

 Instead of the filaments dense conglomerates of 

 irregularly sized opaque regions are observed near 

 the centriole. The nuclear membrane shows a varying 

 appearance in different regions. Partially it seems 

 to consist of a single layer and partially a triple 

 layered structure is evident. 



In the neck region and alongside the convex 

 surface of the head of the spermatid a caudal sheath 

 is found, resembling very closely the caudal sheath 

 described in the cat spermatid by Burgos and Faw- 

 cett (2), or that in the spermatozoon of the edible 

 snail (6). This sheath is thus seen to consist of a 

 cylindrical aggregation of apparently tubular fila- 

 ments. Possibly the function of the caudal sheath is 

 a supporting one as it covers the neck region, where 

 the mechanical strains are at their greatest. The 

 centriole exhibits no peculiarities and is not found in a 

 nuclear indentation as is the centriole of the sea 

 urchin spermatozoon (I). 



The relationship of the two mitochondrial fila- 

 ments and the tail proper was studied on transverse 

 sections of the middle piece. The space enclosed by 

 the cell membrane is divided into two approximately 

 equal half-cylinders, each having its individual mem- 

 brane. One part consists of the eleven tail filaments 

 in the traditional arrangement (4), two additional 

 free filaments and a non-dense surrounding matrix 

 material: the other part consists of the two mito- 

 chondrial filaments embedded in a moderately dense 

 matrix material. The non-dense tail part invariably 



