3-D $+ {t}$ Human Sperm Flagellum Tracing in Low SNR Fluorescence Images

Abstract

Tracing tubular structures from biomedical images is important for a wide range of applications. Particularly, the spermatozoon is an essential cell whose flagella have a tubular form. Its main function is to fertilize the egg, and the flagellum is fundamental to achieve this task which depends importantly on the dynamics of intracellular calcium ([Ca]). Measuring [Ca] along the flagellum in 3-D is not a simple matter since it requires: 1) sophisticated fluorescence imaging techniques dealing with low intensity and signal to noise ratio (SNR) and 2) tracing the flagellum's centerline. Most of the algorithms proposed to trace tubular structures have been developed for multi-branch structures not being adequate for single tubular structures with low SNR. Taking into account the prior knowledge that the flagellum is constituted by a single tubular structure, we propose an automatic method to trace and track multiple single tubular structures from 3-D images. First, an algorithm based on one-class classification allows enhancement of the flagellum. This enhanced 3-D image permits guiding an iterative centerline algorithm toward the flagellum's centerline. Each sperm is assigned an ID to keep track of it in 3-D . Our algorithm was quantitatively evaluated using a ground truth 564 semi-manual traces (six 3-D image stacks) comparing them to those obtained from state-of-the-art tubular structure centerline extraction algorithms. The qualitative and quantitative results show that our algorithm is extracting similar traces as compared with ground truth, and it is more robust and accurate to trace the flagellum's centerline than multi-branch algorithms.

Human sperm uses asymmetric and anisotropic flagellar controls to regulate swimming symmetry and cell steering

“…Furthermore, symmetry (or the lack of it) is a critical proxy to identify sperm capacitation and hyperactivation, which significantly affect fertility ( 10 , 34 , 50 ). Despite numerous efforts to capture the flagellar beat in 3D ( 12 , 14 , 39 – 41 , 46 , 53 – 58 ), the importance of 3D information of the flagellar movement is yet to be fully recognized at the human fertility realm ( 51 ).…”

Multifocal imaging for precise, label-free tracking of fast biological processes in 3D

“…Previous studies of sperm's flagellar 3D beat used light microscopy with a piezo-driven objective or digital holographic microscopy (DHM) 34,38,[58][59][60][61] . The piezo-driven method allows recording up to 180 volumes s -1 35,61 , which represents a third of the sampling speed achieved by our MFI method.…”

Modelling Motility: The Mathematics of Spermatozoa

“…However, with the beating of spermatozoa not always being planar, a natural extension of these approaches is to three-dimensional flagellar motion. Indeed, three-dimensional beating data of high quality is becoming increasingly available in general (Su et al, 2013 ; Wilson et al, 2013 ; Silva-Villalobos et al, 2014 ; Hernandez-Herrera et al, 2018 ; Walker and Wheeler, 2019 ; Hansen et al, 2020 ), with holographic imaging having recently been used to study spermatozoa (Daloglu and Ozcan, 2017 ; Daloglu et al, 2018 ; Muschol et al, 2018 ). We showcase sample 3D imaging from Gadêlha et al ( 2020 ) in Figure 5 , though we note that the work of Gadêlha et al ( 2020 ) has recently been retracted for reasons unrelated to the imaging reproduced here (Shilatifard and Yeagle, 2020 ; Gadêlha et al, 2021 ).…”