170 



J. SCHULTZ-LARSEN AND R. HAMMEN 





Fig. 1. Longitudinal section of the head. Galea capitis con- 

 sists of an outer membrane {a) and an inner one (h), which 

 continues down and lines a cavity in the tip of the head (c). 

 Galea capitis has been forced off the head. On the surface 

 of galea capitis there is an outer membrane approximating 

 50 A which continues down to the basal part of the head (d). 

 Magnification 22,000. 



The inner membrane of the galea capitis forms 

 a pocket lining an acrosomal cavity. At the bottom 

 of this acrosomal cavity is seen a denser struc- 

 ture. The cavity is otherwise filled by a structureless 

 mass that continues into the mass filling up the space 

 between the two galea capitis membranes, and which 

 gives less contrast than the other parts of the head. 



We have sectioned several somewhat shorter heads 

 in a sagittal or oblique plane and have found similar 

 structures, but with acrosomal cavities larger and 

 oval in shape. 



Discussion. — Galea capitis in human sperm is 

 exceptionally delicate and fine in structure — so deli- 

 cate, in fact, that up to now there has been doubt as 

 to whether such a structure was present in mature 



sperm (cf. 5, 6, 12). Electron microscopists, too, have 

 denied its existence in humans (e.g. ref. 8). 



On a few of Retzius (9) pictures of mature human 

 sperm one nevertheless discerns a contour just in 

 front of the equator of the head, which would cor- 

 respond to the rearmost boundary of a hood. Some 

 irregularly shaped heads likewise suggest the presence 

 of a galea in human sperm (cf. 3. plate I, figure 5), 

 which may be hypertrophied relative to the head. 

 Furthermore, Williams (13) is of the opinion that he 

 has observed a loose galea in a single case. 



Phylogenetically the presence of galea in human 

 sperm is a reasonable assumption. It has been pos- 

 sible to prove the existence of a hood in a large 

 number of animals from varying phylogenetic levels, 

 though these hoods have been of diverse shapes and 

 extent, and often occur together with a so-called 

 perforatorium. The presence of a galea in human 

 sperm is also strongly supported by the investiga- 

 tions of Gatenby et al. (2) of spermiogenesis. 



As yet it is impossible to decide upon the function 

 of galea capitis and the acrosomal part of the 

 sperm head. As galea capitis always forms part of 

 the spermatozoa of various types of animals, it 

 might be supposed that, together with the acro- 

 somal part of the head, it has an important part to 

 play with regard to the possibility for the sperm to 

 reach the egg-cell. 



References 



1. Afzelius, Bjorn a., Z. Ze/lforscli. 42. 134(1955). 



2. Gatenby, J., Bronte, J., and Beams, H. W., Quart. J. 



Microscop. Sci. 78, 1 (1936). 



3. Hammen, Rich., Studies on Impaired Fertility in Man. 



Copenhagen and London, 1944. 



4. Hammen, Rich., Schliltz-Larsen,Jorgen, and Carlsen, 



F. E., Feitil. Sreril. 5, 411 (1954). 



5. Held, H., Ber. Verhain/I. sdc/is. Akad. Wiss. Leipzig, 



Math.-phys. Kl. 68, 205 (1916). 



6. Marcus, H., Arch. Zellforsch. 15, 445 (1921). 



7. Papanicolaou, George N. and Stockard, Charles R., 



J. Anat. 24, 37 (1918). 



8. Reed, C. J. and Reed, B. P., Amir. Rec. 100, 1, 1948. 



9. Retzius, Gustave, Biologische Untersuchungen. XV, 



57 ft"., 1910. 



10. Schultz-Larsen, Jorgen, Hammen, Rich., and Carl- 



sen, F. E., Acta Pathol. Microbiol. Scand. 35, 45 ( 1 954). 



11. Sjostrand, F. S., E.yperientia 9, 14 (1953). 



12. Stieve, H., Harn- und Geschlechtsapparat. II. Teil. /// 



W. v. MoLLENDORFF, Handb. der mikr. Anat. d. 

 Menschen 7, 103 (1930). 



13. Williams, W. W., Fertil. Steril. 1, 199 (1950). 



