Table 1.

Histological changes in the human epidermis and dermis 32 days after death.

PMI	Epidermal histology change	Dermis histology change
0–18 h	No obvious change	No obvious change
24 h	The cell layer occasionally showed nuclear pyknosis; no obvious changes were observed in the stratum corneum	No obvious change
36 h	Scattered nuclear fragmentation is seen in the cell layer, showing nuclear pyknosis; the stratum corneum changes as above	No obvious change
48 h	The cell layer occasionally shows nuclear lysis, local visible nuclear pyknosis, rare nuclear fragmentation; local swelling of the stratum corneum	No obvious change
60 h	The cell layer occasionally shows nuclear lysis, local visible nuclear pyknosis, rare nuclear fragmentation; local swelling of the stratum corneum	No obvious change
72 h	The cell layer shows less nuclear pyknosis, visible nuclear fragmentation, rare nuclear dissolution; stratum corneum swelling	There is a small amount of fibre swelling, and there is no obvious change in the whole
84 h	The cell layer shows less nuclear pyknosis, visible nuclear fragmentation, rare nuclear dissolution; stratum corneum swelling	Visible fibre swelling, no significant change in the overall
96 h	Cell layer cell gap widened; more nuclear pyknosis, nuclear fragmentation, nuclear dissolution; stratum corneum changes as above	Visible fibre swelling, no significant change overall
6 d	Cell layer changes as above; the stratum corneum is swollen	Significant swelling of the fibres, visible focal fibre dissolution
8 d	The epidemal layer is thin; the cell layer is basically free of normal cells, with nucleus pyknosis, nuclear fragmentation, and nuclear dissolution; the stratum corneum is swollen, and a purple foam-like stain layer is visible on the surface	The papillary layer fibres are dissolved, the reticulated fibres are arranged in order, the swelling is obvious, and there is focal dissolution
10 d	The local dermis began to separate; the cell layer and stratum corneum changed as above	The papillary layer fibres are dissolved, the reticulated fibres are arranged in order, the swelling is obvious, and there is focal dissolution
12 d	The cells in the cell layer are disorderly, their boundaries are unclear, the number of cells is reduced, and the remaining changes are the same as above	The papillary layer is homogeneous, the woven layer is partially dissolved, and the remaining fibres are swollen
16 d	The number of cells in the cell layer is further reduced, and the remaining changes were the same; there was a contiguous purple-blue staining area at the junction of the epidermis and the dermis; the stratum corneum was severely swollen	Both the papillary layer and the woven layer are homogenized
20 d	The cells in the cell layer are all dissolved, the epidemal is a purple-blue stained area, the stratum corneum changes are the same as above, and the epidemal is mostly separated from the dermis	Both the papillary layer and the woven layer are homogenized
24 d	Completely separated from the dermis, the remaining changes are the same as above	The fibre dissolves into a homogeneous shape, and the papillary layer and the woven layer cannot be distinguished
28 d	Completely separated from the dermis, the remaining changes are the same as above	The fibre dissolves into a homogeneous shape, and the papillary layer and the woven layer cannot be distinguished
32 d	The epidemal disappears, and the purple-blue stained area disappears	Fragmented, flaky