Centriolar defects, centrin 1 alterations, and FISH studies in human spermatozoa of a male partner of a couple that produces aneuploid embryos in natural and artificial fertilization

Elena Moretti,Giulia Collodel,Giuseppe Belmonte,Andrea Menchiari,Raffaella Guazzo,Daria Noto

doi:10.1007/s10815-021-02109-0

Elena Moretti, Giulia Collodel + Show 4 more

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https://doi.org/10.1007/s10815-021-02109-0

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Abstract

PurposeTo study the potential paternal contribution to aneuploidies in the man of a couple who obtained trisomic embryos with natural and assisted fertilization.MethodsSemen analysis, immunofluorescence for localization of tubulin and centrin 1, transmission electron microscopy (TEM), and fluorescence in situ hybridization (FISH) analysis for chromosomes 18 and 9 were performed. Sperm of fertile men were used as controls.ResultsThe percentages of sperm motility and normal forms were decreased. The percentages of sperm with tail reduced in dimension, headless tails, coiled tails, and altered head-tail junction were significantly higher (P < 0.01) in the patient than in controls, whereas the percentage of sperm with a normal centrin 1 localization (two spots in the centriolar area) was significantly reduced (P < 0.01) in the patient. Immunofluorescence with anti-tubulin antibody showed that in most of the patient’s sperm connecting pieces (83.00 ± 1.78%), two spots were present, indicating prominent proximal centriole/centriolar adjunct and evident distal centriole, whereas controls’ sperm displayed a single spot, indicating the proximal centriole. The percentage of sperm with two spots was significantly higher (P < 0.01) in the patient than in controls. TEM analysis showed that centriolar adjuncts of the patient’s sperm were significantly longer (721.80 ± 122.26 nm) than in controls’ sperm (310.00 ± 64.11 nm; P < 0.001). The aneuploidy frequencies of the patient’s sperm, detected by FISH analysis, were increased with respect to controls.ConclusionA paternal contribution to sperm aneuploidies cannot be excluded since the patient’s sperm showed altered morphology, immature centriolar adjunct, presence of evident distal centriole, scarce presence of centrin 1, and high aneuploidy frequency.

Highlights

Embryo aneuploidies can originate from meiotic and mitotic errors [1]
The sperm chromatin immaturity assayed with aniline blue (AB) staining ranged from 50 to 62%
The idea to describe the present case derives from the fact that the couple produced only aneuploid embryos, either with natural or assisted fertilization, and the analysis of spermatozoa showed peculiar defects, in particular in the connecting piece region, despite the fertility of the patient

Summary

Introduction

Embryo aneuploidies can originate from meiotic and mitotic errors [1]. The large maternal contribution to embryo aneuploidies is recognized [2] and, in some way, overshadows the role and clinical relevance of the spermatozoon resulting on a fair consideration of paternal influence to the phenomenon of embryo aneuploidies. J Assist Reprod Genet (2021) 38:1197–1205 such as mRNAs and micro RNAs that may regulate transcription or complement the maternal transcriptome within the cleavage stage embryo [4, 5] Another element that the sperm contributes to the oocyte is the centrosome since human oocyte lacks assembled centrioles [6]. The centriolar adjunct undergoes dynamic changes during sperm maturation, partially or completely disappearing in the mature spermatozoa of different organisms [12] In human spermatozoa, this structure can be visible as microtubule triplets, doublets, and singlets. It has been suggested that the presence of a centriolar adjunct in human sperm cells can be considered a manifestation of incomplete maturation At this purpose, disturbances in proximal centriole morphogenesis, in particular the incomplete disassembly of the centriolar adjunct, can be one of the reasons for embryonic development arrest at the zygote stage [6, 12]

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