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Fig. 3 | BMC Biology

Fig. 3

From: Mechanisms of tethering and cargo transfer during epididymosome-sperm interactions

Fig. 3

Exploration of the kinetics of epididymosome-sperm interaction. a Caput spermatozoa were co-cultured with biotin-labeled epididymosomes and sampled at regular intervals during the course of a 3-h incubation before being subjected to biotin detection. The dominant patterns of biotin localization in the post-acrosomal domain or whole head and mid-piece of the spermatozoa were quantified, with 100 cells being examined per sample (n = 3; graphical data are presented as mean ± SEM), **P < 0.01. bk Two phases of epididymosome-sperm interaction were distinguished, with an initial rapid uptake of biotin-labeled cargo being detected primarily in the post-acrosomal domain within ≤ 5 min of co-culture. bg Fluorescence images representing the different patterns of biotinylated protein transfer detected after a co-incubation period of 5 min are provided. These images depict the gradient of increasing biotin signal, initially being detected in the SAR before extending distally to encompass the entire post-acrosomal domain. hk A second phase of interaction was recorded exclusively with the use of membrane permeant biotin and became particularly apparent during extended incubation (i.e., at either 1 h or 3 h of co-culture). Thus, biotin fluorescence in these cells extended over the whole head and mid-piece of the flagellum. Shown are representative images of the patterns of biotinylated protein transfer detected after a co-incubation period of 3 h. l Schematic of the structural domains of the mature mouse sperm head; EqS, equatorial segment; SAR, sub-acrosomal ring; PAS, post-acrosomal sheath

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