Fig 1.
Measurements of Each Component of the Hip Bone, Sacrum, and Coccyx, and Pelvimetry of the Greater and Lesser Pelvis.
(A) Representative transverse section with MR image showing the connections and articulations in the pelvic skeleton. Pubic symphysis (Ps) was categorized as grade 1, the connection between ilium and pubis in the acetabulum (ip) as grade 3, and the sacroiliac joint (si) as grade 1. (B) Growth of the components of the hip bone, sacrum, and coccyx. The longitudinal length of the pubis, ischium, ilium, and sacrum and coccyx was indicated as LPu, LIs, LIl, and LSC, respectively. Transverse length of the sacrum was indicated as LSTr. (C, D) Pelvimetry for the greater pelvis: The length between bilateral anterior superior iliac spine (LbASIS), length between bilateral femoral heads (LbFH), length of the lateral conjugate (LLC) or the length between ASIS and posterior superior iliac spine (PSIS), subpubic angle (∠SP), and angle of bilateral superior pubic ramus (∠bPu), bilateral ischium (∠bIs), and bilateral ilium body (∠bIl) as shown in the cranial (C) and frontal (D) views of the 3D reconstructed pelvic skeleton. (E) Pelvimetry for the lesser pelvis: the transverse (LTR) and antero-posterior (LAP) diameters of the pelvic inlet as shown in the MR image (transverse section).
Table 1.
Summary of fetal pelvis morphometry.
Fig 2.
Representative Transverse Section with PCXT image at CS17 (A) and CS 21 (B). A) A vague mass with relatively high density was detected around the proximal part of the lower leg, which may correspond to mesenchymal condensations that form into a template for later chondrification. B) Chondrification of the hip bones, femur, and sacrum was detected.
Fig 3.
3D Reconstruction of Cartilage Formation in the Hip Bone.
The acetabulum was located at the center of the illustration. CS, Carnegie stage; EF, early fetus. Green, pubis; Purple, ilium; Yellow, ischium. Pink in EF (75 mm) indicates the ossification center in the ilium. The number in parentheses indicates the CRL (mm). The scale bar indicates 1 mm.
Fig 4.
Cartilage Formation in the Sacrum and Coccyx.
Three-D reconstruction of the sacrum and coccyx. Ventral view, lateral view, and transverse section at S1 are shown. CS, Carnegie stage; EF, early fetus. Light blue, coccyx; Red, sacrum. Scale bar indicates 1 mm.
Table 2.
Connection of the Sacrum-Coccyx Column in Each Sample.
Fig 5.
The Growth Speed of Each Component of the Cartilage.
(A) Longitudinal length of the ilium (LIl), ischium (LIs), and pubis (LPu), and longitudinal (LSC) and transverse (LSTr) length of the sacrum-coccyx according to CRL. The lengths measured are shown in Fig 1A. (B) The angle of the bilateral superior pubic ramus (∠bPu), bilateral ischium (∠bIs), and bilateral ilium (∠bIl) measured according to CRL, indicating the orientation of the growth.
Fig 6.
Three-D reconstruction of cartilage formation in the pelvic skeleton (frontal view). Blue, femur; Green, pubis; Light blue, coccyx; Orange, aorta and common iliac arteries. Purple, ilium; Red, sacrum; Yellow, ischium. The number in parentheses indicates the CRL (mm). The scale bar indicates 1 mm. See also S1–S6 Videos.
Table 3.
Connections and Articulations of Each Cartilage in Each Sample.
Fig 7.
(A) Length between bilateral anterior superior iliac spine (LbASIS) and length between bilateral femoral heads (LbFH) according to CRL. (B) Length of the lateral conjugate (LLC) according to CRL. (C) Subpubic angle (∠SP) according to CRL. The lengths and angle measured are shown in Fig 1B and 1C.
Fig 8.
Pelvimetry of the Lesser Pelvis.
(A) Transverse diameter (LTR) and antero-posterior diameter (LAP) of the pelvic inlet according to CRL. The lengths measured are shown in Fig 1D. (B) LTR/LAP ratio according to CRL. (C) Two representative cross-sectional MR images of the pelvic inlet of the lesser pelvis. Note the variation of the LTR/LAP ratio between the two samples.