Cara Sara....buon giorno dopo L'Aquila!

If you wanted, I could show you personally (:-)) ......  to be honest: it would be a 3-4 or even more pages work to describe the 'best protocol' to cut ultrathin sections of human embedded spermatozoa....(please be cautious when you are cutting those spermatozoa embedded in the human...(:-)).

My two cents for now: you ought to give details of your specific situation with the method, the instrumentation you have at your disposal, the specimen blocks (you deal or have to deal with...):

1) specify at least in brief your spec-prep-protocol (from fixatve/fixation to infiltration, embedding, polymerisation),

2) embedding resin (type, mixture: hard, middle hard, soft - or -percentage/volume/weight of its components), embedding moulds, or round-capped or pyramidal beem capsules (depending on your choice), centrifugation before polymerisation....

3) type of ultramicrotome, experienced user of or beginner (or: are you perhaps in a comfortable situation to hand over that job to an experienced tech?  if the latter you should have no problem at all....)

4) cutting angle, cutting speed, trimming of specimen block surface prior to sectioning, 'semithin' sectioning for a first orientation whether spernmatozoa are included in the section level or not and overview LM-staining, catching sections, be it semithin sections or ultrathin sections, out of the knife trough....section thickness needed or (for modern TEMs) acceptable....

5) Grids, grid films, mounting sections unto the grids, single sections, serial sections? Staining, and examination in the TEM (which one....) etc. etc....  

The reader of your questions appreciates any detail in order to be of help. 

so:  what is your problem (and don't forget: your problems may start at the point you are liquefying human sperms/ejaculate prior to sedimentation and immediate fixation....)

Only mentioned for your convenience:   cf:

Fujita, T., Miyoshi, M. & Tokunaga, J. Z. Zellforsch. (1970) 105: 483. doi:10.1007/BF00335423, unfortunately PPV (pay per view) see the 'References' @ http://link.springer.com/article/10.1007%2FBF00335423?LI=true

Really specific - also with regard to your ultimate question - and 'almost' in Italian:  "A simple and reliable method to prepare semen for transmission electron microscopy" by M. Relucenti, L. Petruziello, G. Familiari and R. Heyn (Laboratory of Electron Microscopy Pietro M. Motta, Department of Anatomy, Sapienza University of Rome, Via Alfonso Borelli, 50, 00161 – Rome, Italy) in: Microscopy: Science, Technology, Applications and Education, A.Méndez-Vilas

and J. Díaz (Eds.) ©FORMATEX 2010 151, @ http://www.formatex.info/microscopy4/151-155.pdf

Furthermore, this one also includes valuable information (FREE ACCESS):

D Nogueira et al, ‎1999: Light and electron microscopic analysis of human testicular spermatozoa and spermatids from frozen and thawed testicular biopsies

https://academic.oup.com/humrep/article/14/8/2041/2913232/Light-and-electron-microscopic-analysis-of-human. Hum Reprod (1999) 14 (8): 2041-2049.

DOI: https://doi.org/10.1093/humrep/14.8.2041.  Found @  https://academic.oup.com/humrep/article/14/8/2041/2913232/Light-and-electron-microscopic-analysis-of-human (html)  or also as  .pdf @ https://academic.oup.com/humrep/article-pdf/14/8/2041/11496245/142041.pdf. In the references of that valuable article you can find also cited a great Atlas of..(containing also some practical hints and tipps for preparation ,embedding and sectioning (if I remember correctly):  Holstein, A.F. and Roosen-Runge, E.C. (1981) Atlas of Human Spermatogenesis. Ed. Grosse Verlag, Berlin. (perhaps you'll find an example in your library or by loaning and/or by using a second hand bookshop (better: 'antiquarian bookseller').

Good luck, my best wishes, and compliments,

cordiali saluti di Salisburgo e buona giornata,  Wolfgang

Hi

In clinical practice, essentially mechanical methods are used to retrieve spermatozoa from the testicular tissue, and biopsies are usually frozen as shredded suspensions. If the tissue is frozen as whole biopsies it may either be shredded after thawing, or enzymatic digestion (collagenase type IA or IV) may be used as an alternative method of sperm recovery . Other studies describe different attempts to preserve testicular spermatozoa, such as freezing of seminiferous tubules  or single spermatozoa in empty zonae of human and hamster oocytes . Histological evaluation of spermatogenesis after thawing requires freezing of the whole biopsy .